Dunno if you're noticed, but Nasrallah is just one of a few thousand Hezbollah members who have been killed or seriously injured recently, along with lots of weapons caches.
Killing one person is obviously not (usually) going to make a big difference. Killing all of them does. As the article correctly argues.
Anyway, the goal here for Israel is to get to the point where people can return to their homes in northern Israel. To achieve that if there's still Hezbollah members around, they just need to invade southern Lebanon and turn it into a demilitarized zone, putting northern Israel out of reach.
Similar to what Ukraine has done by invading Kursk, Russia.